Process for supplying oxygen and/or nitrogen and also argon to a geographic zone

Abstract

In a process for supplying oxygen and/or nitrogen and also argon to a geographic zone, the geographic zone comprising n units for air separation by cryogenic distillation, of which a first unit and n-1 second units produce oxygen and/or nitrogen but do not produce argon, the oxygen and/or nitrogen for at least certain clients come from at least one of the n-1 second, non-argon-producing units, and argon for these clients comes from the first unit, where the first unit operates by means of a column system comprising a double column composed of a higher pressure column operating at a first pressure and a lower pressure column, whose bottom is connected thermally to the top of the higher pressure column, operating at a second pressure, which is lower than the first pressure, and of an argon-producing column and a mixing column, wherein the mixing column is fed at the bottom with an auxiliary gas consisting of gaseous nitrogen from the first or the lower pressure column, and at the top with a liquid which is richer in oxygen than the auxiliary gas and is taken from the lower part of the low-pressure column, and impure oxygen constituting a production gas is withdrawn at the top of the mixing column, the argon-producing column is fed with an argon-enriched gas flow from the lower pressure column, and an argon-rich product is withdrawn from the argon-producing column.

I claim: 
     
         1 . A process for supplying oxygen and/or nitrogen and also argon to a geographic zone comprising n units for air separation by cryogenic distillation, the process comprising the steps of:
 providing a first unit and n-1 second units;   using the first unit to supply argon demands of clients within the geographic zone;   using the n-1 second units to produce oxygen and/or nitrogen without producing argon, wherein the oxygen and/or nitrogen for at least certain clients in the geographic zone come from at least one of the n-1 second, non-argon-producing units, and argon for these clients comes from the first unit,   wherein the first unit comprises a column system comprising a double column composed of a higher pressure column operating at a first pressure and a lower pressure column, whose bottom is connected thermally to the top of the higher pressure column, operating at a second pressure, which is lower than the first pressure, an argon-producing column, and a mixing column;   feeding a bottom of the mixing column with an auxiliary gas comprising gaseous nitrogen that is transferred from the higher pressure column or the lower pressure column,   feeding a top of the mixing column with a liquid, which is richer in oxygen than the auxiliary gas, that is transferred from a lower part of the lower pressure column;   withdrawing impure oxygen constituting a production gas at the top of the mixing column;   feeding the argon-producing column an argon-enriched gas flow from the lower pressure column; and   withdrawing an argon-rich product from the argon-producing column.   
     
     
         2 . The process according to  claim 1 , wherein the argon for these at least certain clients comes solely from the first unit. 
     
     
         3 . The process according to  claim 1 , wherein at least some of the n-1 second units are halted if the price of electricity increases beyond a threshold. 
     
     
         4 . The process according to  claim 3 , wherein the first unit is not halted if the price of electricity increases beyond the threshold. 
     
     
         5 . The process according to  claim 1 , wherein the post-halt steady-state return time for one or even each of the n-1 second units is less than that for the first unit. 
     
     
         6 . The process according to  claim 1 , wherein the first unit does not supply the clients that it supplies with argon with oxygen. 
     
     
         7 . The process according to  claim 1 , wherein the first unit supplies all of the clients in a zone with argon and/or constitutes the only unit supplying the clients in the geographic zone with argon. 
     
     
         8 . The process according to  claim 1 , wherein the first unit receives a flow of air for separation which is greater than that needed to produce a flow of oxygen that it produces as an end product. 
     
     
         9 . Assembly of units for air separation by cryogenic distillation for supplying oxygen and/or nitrogen and also argon to a geographic zone, the assembly comprising:
 n units for air separation by cryogenic distillation, of which a first unit and n-1 second units produce oxygen and/or nitrogen but do not produce argon;   means for transporting the oxygen and/or nitrogen for at least certain clients in the geographic zone from at least one of the n-1 second, non-argon-producing units; and   means for transporting argon for these clients from the first unit;   wherein the first unit operates by means of a column system comprising:
 a double column composed of a higher pressure column operating at a first pressure and a lower pressure column, whose bottom is connected thermally to the top of the higher pressure column, operating at a second pressure, which is lower than the first pressure, and of an argon-producing column and a mixing column; 
 means for feeding the mixing column at the bottom with an auxiliary gas consisting of gaseous nitrogen from the first or the lower pressure column, and means for feeding the mixing column at the top with a liquid which is richer in oxygen than the auxiliary gas and is taken from the lower part of the low-pressure column; 
 means for withdrawing impure oxygen constituting a production gas at the top of the mixing column, 
 means for feeding the argon-producing column with an argon-enriched gas flow from the lower pressure column, and 
 means for withdrawing an argon-rich product from the argon-producing column.